Hadn't thought about 40G/100G ethernet. It'd definitely be in that same area for doing that. I'd definitely agree that the obstacles at this point are either minor or a "why bother" kind of thing. With speeds continuing to go up, I'd expect it in a generator or two simply because the "why bother" will shift the other way, why bother to make a new standard when this one does it too and is nearly ubiquitous. My guess at least for peripherials is going to be in the optical thunderbolt area, more because of the way the device network matches what people are designing for anyway. I'd guess once there's two standards, a local (optical pcie) and remote (optical ethernet), things might begin converging more and more until it's less distinct between the two.

I'd expect optical more because it's easier to get high bandwidth and low latency on interconnects than copper because of the lower crosstalk and everything. It's just a question of market forces pushing things to converge.